Corrosion resistant nickel-base alloy



Patented Nov. 19, 1940 PATENT OFFICE CORROSION RESISTANT NICKEL-BASEALLOY Claude R. Bishop, Niagara Falls, N. Y., assignor to HaynesStellite Company, a corporation of Indiana No Drawing. Originalapplication August 24,

1939, Serial No. 291,672. Divided and this application April 12, 1940,Serial No.'329,263

5 Claims.

to solutions of hydrochloric acid. Alloys of the foregoing type aredisclosed in Patents 1,514,064 and 1,753,904, issued to A. J. Mandelland C. E. Plummer, respectively. While extensive use has been made ofthe excellent resistance of such alloys to corrosion by hydrochloricacid, there is a demand for alloys having even greater resistance tothis acid.

The principal object of this invention is to provide a nickel-base alloyhavingimproved corrosion resistance, particularly to hydrochloric acid,

and good physical properties. This and other objects are attained in thepresent invention by the application of mydiscovery that the addition ofantimony, within certain definite composition limits, greatly improvesthe corrosion resistance and other properties of the nickel-base alloys.

Alloys included in the invention contain silicon in a proportion between3% and 14%, preferably between 6% and 11%; antimony in a proportion 5between 0.02% and 10%, preferably between 0.3%

and 5%; copper in a proportion between 0.05% .and 25%, preferablybetween 1% and 4%; with or without aluminum in a proportion between0.02% and 5%, preferably between 0.5% and 3%;

5 remainder nickel which may be partly replaced.

by cobalt or iron or both. In addition to the foregoing elements a smallproportion of manganese may be present to improve the hot workingcharacteristics of the alloy.

w v The following table indicates the composition of severalrepresentative alloys of the invention and also indicates the results ofcorrosion tests made on samples of those alloys and on samples of alloyscontaining no antimony but otherwise sim- I ilar to those of theinvention.

Corrosion rate in milligrams per square cen- Composition (remainder Ni)gg gg $9 32 3; H0] at a temperature of 70 C.

First Second Third 3 si Cu Al Sb 4s 4 4s 7 hours hours hours Per Per Percent cent cent 3 None None 0.76 0. 77 3 None None 0.6 0.5 0.5 3 None 0.34 0 45 0. 33 0. 23 3.4 None ,0.5 0.44 0.27 0.22 3 None 1. 7 0.31 0. 220. 41 3.1 None 3.5 0.34 0.39 3. 1 None 7. 0. 23 0. 27 3.5 3.8 None 0. 480. 31 2. 9 3. 2 2. B 0. 24 0.-l1 13. 7 3. 7 Y 1.4 0. 38 0. 48

Not tested.

The corrosion rates shown in the above table were determined bycompletely immersing the specimen in the acid solution indicated thereinand maintaining that solution at constant temperature for the periods oftime indicated. The loss in weight was determined and reported as thenumber of milligrams dissolved per square centimeter of surface per hourof time.

The addition of 0.3% to 5% antimony to the alloys described herein, inaccordance with the preferred procedure of the invention, does notmaterially afi'ect their mechanical properties, but greater proportionsof antimony, that is, between 5% and usually lower the strength of thealloy somewhat. However, in either instance thealloys possess excellentcorrosion resistance, and in apparatus constructed from alloyscontaining the greater proportions of antimony a proper allowance in thedesign of such apparatus may be made to compensate for the decrease instrength of the alloy.

I claim:

1'. An alloy comprising silicon in a proportion between 3% and 14%;copper in a proportion between 0.05% and 25%; antimony in a proportion,between 0.02% and 10%, serving to impart improved corrosion resistanceto the alloy; the

remainder substantially all nickel.

5. An alloy comprising silicon in a, proportion between 6% and 11%;copper in a proportion between 1% and 4%; antimony in a proportion,between 0.3% and 5%, serving to impart improved corrosion resistance tothe alloy; remainder nickel.

R. BISHOP.

antimony is in a proportion between 0.3% and v 5%. I

